The primary, service-oriented goal of the Exposure Assessment Core is to provide a high-quality, comprehensive and cost-effective resource in exposure assessment for all of the research projects within the Center. The secondary, research-oriented goal is to develop and evaluate new approaches to the assessment and quantification of children's exposures to EDs and other developmental toxicants in the urban environment. Objectives of the core, which remain unchanged since the previous application, are to do the following: ascertain new developmental toxicants in the urban environment; identify and develop markers of exposure that will permit precise individual assessment of environmental exposures in infants and children; quantify children's exposures to known environmental toxicants, using analyses of environmental as well as of biological samples; evaluate and quantify exposure pathways; access and store environmental and biological samples; and provide quality assurance/quality control (QA/QC) for all analyses conducted in Center projects.